Welcome to the Team!
Advise I give is always the same. Buy the best (least rust and straight metal not slathered a half inch deep in Bondo) that you can afford. Can't weld in a patch panel, or worse there are no patch panels for your year and model, then follow my modified Horace Greeley advise "Go South-west young man!". There is no rust in the desert south west because they don't have any water, (lot of sun that destroys interiors, and few rattle snakes), but no rust on the cars that were shipped there and never left.
Don't worry about the power train, but if you want a manual trans try and find a car with a manual to get rare parts like clutch pedals linkage and springs. You can buy a crate motor today at any power level you want cheaper than you could build one from a pile of parts.
Like I said the sun is murder on interiors (cloth turns to dust, foam rubber and plastic to powder), so a mid-west farmer's car that spent the last fifty years stored under the hay loft will have a pristine interior, even if there is no metal left below the belt line of the car.
It might take more than two project cars depending upon year and model as some are more popular than others.